Add -R, --recursive option for implying --mode inplace and all *.hs file under given directory

[evan0greenup]

Is your feature request related to a problem? Please describe.

For modern Haskell usage, reformatting a whole haskell project is certainly more often then single file. according to the README.md, ormolu --mode inplace $(find . -name '*.hs') or ormolu --mode inplace $(git ls-files '*.hs') is too long and inconvenient for user to input.

Describe the solution you'd like
A -R or --recursive option would works. It implies --mode inplace and the path on the end will be the directory to make recursive reformatting.

Unlike ormolu --mode inplace $(find . -name '*.hs'), -R can identify scm repository. If the path is located inside Git workspace or Mercurial workspace. It can automatically ignore the files which is ignored by .gitignore spec.

Describe alternatives you've considered
It would be good to referencing black for python https://github.com/psf/black

Additional context
The final functionality should like this

$ cd haskell-sample-project/
$ ormolu -R .
totally 150 *.hs files found, 23 *.hs file reformated!!!

[amesgen]

See #691, #697, #910 for prior discussions on this topic, and #1054 for a related discussion.

[mrkkrp]

Closing as a duplicate of #691. I'm not sure how exactly ormolu --mode inplace $(git ls-files '*.hs') is too long or inconvenient. It is already a one-liner, and it can be further shortened if you create a bash alias. Personally, I made this little function in Nushell:

# Format all Haskell files in the current git repository.
def "ormolu all" [] {
    ormolu -i (git ls-files '*.hs' '*.hs-boot' | lines)
}

I do see that there has been multiple requests like this, but the correct implementation here would need to

• call git ls-files at least in some cases, since you seem to accept that excluding gitignored files is a desirable feature; or
• re-implement the logic of git ls-files.

Otherwise there is a host of extra settings we would need to think about, such as what to do with symbolic links when we traverse a directory tree.

I prefer to avoid dealing with this complexity in an already pretty complex project.